Try this. Flex your upper arm muscle (bicep). You'll notice that when you do that your arm bends at the elbow and your forearm moves upward towards the chest or shoulder. This is what your muscles do and how they work. When you have a tightened muscle, it is like always flexing your bicep, on a somewhat lesser extent. Imagine you have tense muscles in your back (if you don't already). These are connected to the spine from the neck to the pelvis. The tense muscles will pull at and contort the vertebrae of the spine resulting in pinching nerves throughout the spinal column. Since all nerves run through the spinal column any that may be pinched can cause pain or illness.
Spasms are usually the result of two muscles fighting against another. One tense or tight muscle pulls at a weak or loose muscle. It can result in very uncomfortable twitching and pain. You can alleviate the pain by strengthening the weaker muscle; however, if proper stretching is not done this can weaken the tightened muscle. Can you see the dilemma?
Your chiropractor will examine all aspects of your life besides your back. He will ask questions about your family history and your daily routine as well as performing palpation and neurological tests to determine what is causing your ailment. With that information, he can prescribe a treatment program that will help alleviate the muscle tightness that bothers you. Imagine getting a prescription to go to a massage therapist. Doesn't that sound wonderful?